More Postop Afib, Same Stroke Risk When LAA Exclusion Added to Cardiac Surgery: Study

Marlene Busko

December 07, 2016

ROCHESTER, MN — Among patients who underwent routine cardiac surgery not related to atrial fibrillation (AF), those who also had prophylactic left atrial appendage (LAA) closure—ostensibly to reduce their risk of stroke—had an increased risk of early postoperative AF (within 30 days) with no gains in long-term survival or freedom from stroke, in a new study[1].

Specifically, patients who had LAA exclusion during surgery had a fourfold higher risk of early postoperative AF compared with patients who had surgery without LAA exclusion, and both groups had the same rates of stroke and survival during a median follow-up of 9.1 years (up to 14.6 years).

Thus, "it remains uncertain whether prophylactic exclusion of the LAA is warranted for stroke prevention during non–AF-related cardiac surgery," Dr Rowlens M Melduni (Mayo Clinic, Rochester, MN) and colleagues summarize, in an article published online November 30, 2016 in Circulation.

Invited to comment to heartwire from Medscape, Dr Hugh Calkins (Johns Hopkins Hospital, Baltimore, MD), vice chair of the writing committee and Heart Rhythm Society representative for the 2015 ACC/HRS/SCAI Left Atrial Appendage Occlusion Device Societal Overview[2], was not surprised by the finding of increased early postprocedure AF after LAA occlusion, since there is additional inflammation associated with the procedure.

What is "interesting" is that several recent studies have proposed that elimination of the appendage lowers the risk of subsequent AF, he noted. "This study provides a word of caution regarding leaping to conclusions. . . . Given the infancy of this field, we must take one step at a time."

Melduni and colleagues agree that "future studies are needed to evaluate the long-term efficacy of LAA-closure strategies in reducing the risk of stroke in patients with AF."

To heartwire , senior author Dr Samuel J Asirvatham (Mayo Clinic) speculated that the LAA closures may have been incomplete, which allowed more thrombi to form. Thus, "further study is needed to see whether improved techniques with full closure of the appendage may prevent stroke," he added.

Occluding LAA to Try to Lower Stroke Risk

The LAA is an important source of thrombi in patients with AF, and it is often prophylactically occluded during cardiac surgery to try to reduce the risk of stroke, but the clinical impact of this strategy is unknown, Asirvatham said.

Moreover, the LAA acts as a decompression chamber for the left atrium, and animal studies have suggested that LAA closure could paradoxically increase the risk of early postoperative AF and potential stroke.

Thus, the researchers analyzed early postoperative AF as well as stroke and mortality outcomes in 9729 patients who had CABG and/or cardiac-valve surgery with or without LAA closure at the Mayo Clinic from 2000 through 2005.

One staff surgeon routinely performed LAA ligation during mitral-valve surgery, but otherwise LAA closure was performed primarily in patients with AF or LAA thrombus.

The LAA was closed by ligation (oversewing or stapling) in almost all (98%) of the patients who underwent this added procedure, and it was excised in the remaining 2% of patients who had this procedure.

The study patients had a mean age of 65 and 68% were male.

About half of the 469 patients (48%) who underwent LAA closure had a history of AF; most had mitral-valve surgery (63%), and the rest had combined CABG and valve or other cardiac surgery (19%), aortic-valve surgery (12%), CABG alone (4%), or tricuspid-valve surgery (2%).

Only 14% of the 9323 patients who did not undergo LAA closure had a history of AF; most had CABG alone (42%), and the rest had aortic-valve surgery (26%), combined CABG and valve or other cardiac surgery (17%), mitral-valve surgery (13%), tricuspid-valve surgery (2%), and pulmonary-valve surgery (0.1%).

A total of 461 patients who had LAA closure were matched with 461 other patients with similar characteristics.

A third of all patients developed AF within 30 days of surgery.

In the propensity-matched cohort, twice as many patients in the LAA-closure group vs the others developed early postoperative AF (69% vs 32%, P <0.001).

Rates of surgical complications were similar in both groups: bleeding requiring surgery (4%), pneumonia (3%), and acute renal failure 4%.

A total of 65 patients (7.1%) developed ischemic stroke, and 395 patients (43%) died during follow-up.

The rates of stroke at 30 days (0.9% vs 1.0%), 1 year (2.7% vs 4.6%), and 5 years (9.6% vs 10.7%) were similar in patients who had undergone LAA closure vs matched patients who had not (all P>0.10).

Similarly, the 30-day mortality for patients who had vs did not have LAA closure was 2.5% vs 5.2%, respectively, and the 5-year mortality was 27% in each group (all P>0.10).

Outcomes After Cardiac Surgery With vs Without LAA Closure*

Outcome OR (95% CI) P
Postoperative AF within 30 d 3.88 (2.89–5.20) <0.001
Stroke within 9.1 y 1.07 (0.72–1.58) 0.74
Mortality within 9.1 y 0.92 (0.75–1.13) 0.43
*In propensity-matched cohort, after adjustment for multiple confounders

Need to Evaluate LAA Closure, Too Soon to Forgo Anticoagulation

"This study would suggest that a similar evaluation of all LAA-occlusion techniques should be undertaken," the researchers conclude.

That is,  more research is needed on outcomes after LAA occlusion with investigational or approved devices including the Sentinel (Aegis), WaveCrest (Coherex Medical), Lariat (SentreHEART), Amplatzer Amulet (St Jude Medical), AtriClip (AtriCure), and Watchman (Boston Scientific) devices, Asirvatham added.

"The field of appendage closure with devices and procedures is in its infancy," Calkins noted. "What is exciting is that we now have a number of options available, including Watchman, Lariat, Atriclip, and other surgical and catheter-based procedures."

These procedures are clearly reserved for patients at high stroke risk who cannot take anticoagulants due to long-term bleeding or fall risk, he continued. "Over time it is possible that appendage closure may prove to be an alternative to anticoagulation for preference reasons. But we are not there yet."

Given these findings, "it is unclear whether anticoagulant therapy can be safely discontinued without further data showing that elimination of the LAA from the systemic circulation does indeed reduce the incidence of stroke in patients with AF," Melduni and colleagues agree.

It is also difficult to interpret the impact of appendage closure on long-term stroke and mortality given the propensity-matched design on this study, Calkins cautioned. "At the end of the day, there is no substitute for a prospective randomized clinical trial."

The authors have no relevant financial relationships. Calkins is a consultant for Medtronic, Abbott Medical, Atricure, and Boehringer-Ingelheim and has received research grants from Medtronic and St Jude Medical.

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